What happens to the drive motor when the room temperature is raised to +30°F and then pulled back down to -10°F?

When the room temperature is raised to +30°F and then pulled back down to -10°F, the drive motor experiences a change in load conditions. During the pull-down process, the refrigeration system must work harder to remove heat from the space, which results in an increased refrigerant flow and a higher heat load. This causes the motor to draw more amperage to meet the demand for cooling.

As the temperature difference between the desired temperature and the actual temperature increases, the system must overcome greater resistance to achieve the cooling effect required. Consequently, this leads the drive motor to operate at a higher current draw, which is reflected in the increased amperage.

The other options do not accurately describe the motor's behavior during this scenario. For instance, the drive motor will not shut down completely unless there is a malfunction or protective mechanism triggered by excessive load or other issues. While it's desirable for the motor efficiency to increase in certain conditions, in this case, the increased amperage pull signifies that it is working harder, not necessarily becoming more efficient. Lastly, saying the drive motor will operate without any change doesn't account for the varying load conditions due to the temperature fluctuations, which clearly affects its performance.